Rosin treatment



- Patented Aug. 27 1946 OFFICE 2,406,338 Rosm TREATMENT Laszlo Auer,South Orange, N. 'J.

No Drawing. Application October 2'7, 1943, Serial No. 507,895

3 Claims. (Cl. 260-106) GENERAL FIELD or INVENTION AND STATEMENT orOwners to about 168, and in their natural state they-are ordinarilyhard, brittle materials, of melting point from about 70 C. to about 85C.

' Rosin is a valuable raw material for a number of commercial purposes,such as in paper sizing, soap manufacture, and especially in thecoatings and plastics industries. There are, in fact, 2.

- plastic compositions.

number of examples in the art of use of various 1 rosin derivatives forpurposes such as those mentioned, Some of the most important and commonexamples occur in the coatings industry, 1. e., use :11; rosinderivatives in paints, varnishes and the In its natural state, however,rosin is not well suited to many commercial purposes for which it ispotentially a valuable raw material.

The primaryobiect of the present invention is to modify various physicalproperties of rosin, whereby to produce modified rosin products whichare better adapted to many uses for which rosin or rosin derivatives arenow employed. In addition, the modifications, brought about inaccordance with the present invention make it possible and advantageousto use the modified rosin products for many purposes for which rosin inits natural state and also various derivatives thereof are not wellsuited.

To illustrate, reference is made to coating compositions, such asvarnishes. In its natural state, rosin is a brittle material andtherefore yields a brittle film when employed alone .as varnish solids.Thus, rosin in its natural state does not have film formingcharacteristics such that it may satisfactorily be employed alone asvehicle solids in a. coating composition. According to this invention,modifications are brought about in the rosin so as to secure a rosinproduct having drying or film forming characteristics which are wellsuited to the coating composition industry, thereby even making possibleemployment of the modified rosin products alone as vehicle solids invarnishes and the like. Usually, however, at least some drying orsemi-drying oil is advantageously used with the modified products.

Because of the improved properties of the modified rosin products, suchproducts may be employed as a replacement ingredient, in substantialproportions, for linseed or other drying or semi-drying oils in paintsand other coating and For certain special purposes in .the soap andpaper sizing industries, the modified rosin prodacts of the inventionmay also be of advantage, notwithstanding the'fact that the modifiedproducts have a reduced acid value.

One of the most important modifications brought about by the process ofthe invention is the softening Or liquefying of the rosin. i.e.. atleast some reduction of brittleness or in melting point, or both. Inaddition, the process of the invention is notable in its efi'ect on theacid value, the invention providing for appreciable reduction in acidvalue, as will further appear. In referring to changes of this type andin making comparisons of the modified products with products not treatedwith modifying agents, it is to be understood that the statementsregarding changes and comparisons are always made on the basis of arelation between the producttreated with a modifying agent and a producttreated in exactly the same manner (heating, etc.) but/without amodifying agent.

According to the invention, by appropriate control of treatmentconditions, and by appropriate selection of materials, the degree ofsoftening or liquefaction and also of acid value may be regulated tomeet various different requirements, For instance, according to theinvention, it is possible-to very extensively soften the rosin, or tovery extensively lower the acid value, or both.

Although the invention is not limited thereto, it is of especialimportance and advantage in accordance with the invention to subject therosin' to treatment for a time and under conditions such as to changethe physical character of the rosin from its natural hard and brittlecondition to a consistency approximating the so-called "cold fiow, i.e., a consistency according to which the material will gradually flow atnormal room temperatures, so that if a blob of .the modified rosin iplaced on a flat surface, it will more or less-gradually flatten out,often at a rate which is not observable withthe eye. For many purposes aliquefaction sirable.

For certain p p ses it isadvantageous that at least to this degree isde- .classes of agents perature the rosin be liquefied even to theextent of becoming a mobile liquid, similar, for instance. to

' the consistency of certain oils. such as bodied The process of theinvention involve heating the rosin in the presence of sulfurdioxide,-the duration of heating, temperature and other treatmentconditions, being such as to eflect. decarboxylation or softening of therosin, and being controlled in accordance with the extent and type ofmodification desired.

In addition to sulfur dioxide other modifying agents may be present,such for example as the following inorganic acids which promotedecarboxylation:

. Hydrochloric Hydrobromic Hydriodio Sulphuric Chlorsulphonic Sulphurous(H2803) Hydrosulphuric (HzS) Hydrosulphurous Thiosulphuric Boric-Phosphoric Hydrocyanic Thiocyanic Moreover, any one of many otherdecarboxylation promoting agents may be present, such as organic acids,metal salts, and other groups and as disclosed in various of my priorpatents including those patents mentioned elsewhere herein, for examplePatent No. 2,298,270.

The treatment in is desirably carried the presence of sulfur dioxide outeither under positive presthe gas through the reaction vacuum.

By selection of modifying agents, and by appropriate variations intreatment procedure, time, temperature, etc.,. I am enabled to producemodified rosin products having quite a wide range of properties. Infact, according to the invention, it is possible to secure a modifiedprod- I uct in which either theacid value or melting point is veryextensively lowered, or in which both of these properties aresimultaneously lowered to a great extent. Various of the decorboxylationpromoting agents are notable in mak-v ing possible extensive lowering ofmeltingpoint, so that in many instances liquid products are obtainable.

In carrying out the procesathe rosin i' -heated in the presence of thesulfur dioxide at tembetween about 100 c. and about 350 0., dependingupon the materials used and the degree of modification desired. Usuallythe temperature should be at least 250 C. and most frequently above 270C. in order to secure appreciable modification of the properties of therosin.

Throughout the heating period the percentage of sulfur dioxide bubbledthrough or otherwise brought in contact with the rosin may be anywhereup to about 30% 4' even more, although usually not more than about .willbe absorbed by the reaction mass.

The percentage of other modifying agents present during treatment withsulfurdioxide, such as the decarboxylation promoting agents abovereferred to, may be anywhere from a trace, for

instance, from .0l% or .5% up to about 10% by weight of the rosin beingtreated, and I have found a particularly advantageous range to be fromabout 1%. or 2% up to about 5%.

The effects of certain variations in temperature, percentage ofmodifying agent and time will be pointed out more fully hereinafter.

Thorough dispersion of the modifying agent in the rosin is of importanceand appropriate control of temperature and ,time both contribute tobringing about such thorough dispersion. Agitation may be employed as anaid to securing thorough dispersion. Usually not more than a few hourstreatment on temperature will be found suiilcient, for instance, fromabout one hour to about five hours, although in some cases, the reactionproceeds very rapidly, requiring not more than about one-half hour.

Another important consideration is that the reaction is preferablycarried out in the absence of air, or out of contact with anysubstantial quantity of air. For this purpose the reaction may becarried out in a closed vessel, though not necessarily at a positivepressure, so that the gases or fumes of theraction released from themodi-'- fying agent servejto exclude the air.

Vacuum is also effective for the purpose of excluding air and, inaddition, reduction in contact of .air may be brought about byblanketing the surface of. the reaction mixture with some 1 inert gas,such as CO2, or nitrogen. Where vacuum is-used, a pressure, forinstance, of about 100 mms. Hg to about 45 0 mms. Hg will be foundeffective, although higheror lower pressure may be used, under variouscircumstances.

Some. more or less general considerations regarding the process shouldbe noted, as follows:

Although the complete mechanism of modification may not be fullyunderstood, it may be mentioned that rosin is an organic isocolloid, i.e.. a colloidal system in which the dispersed phase and the dispersionmedium are both of the same chemical composition, though present indifferent physical states.

By modification I believe that the relationship or relative proportionsof the dispersed Phase and dispersion medium may be altered. Moreover,the

modification process apparently also involves decarboxylation, theextent of which is usually inmers are formed.

Some of the foregoing effects or reactions (particularly with respect tothe physical consistency of the modified product) may work in onedirection and others in the opposite direction.

In considering the nature of the modifications,-

it is to be noted that, While some small loss in weight may occur byvolatilization (usually not more than about 15-20%), no appreciablefractional or destructive distillation takes place. With appropriateprecautions to avoid distillation the process can usually be carried outwithout loss or .more than 5% or 10%, such small loss as does occurusually comprising water, CO2, etc.,

' at least in major part. Asa precaution, the temperature should be keptbelow the boiling or distillation point of the main reaction product,under by weight of the rosin or the applied reaction conditions of theprocess.

By this precaution, destructive distillation or cracking is positivelyavoided.

The modified rosin product is quite'unique, since the rosin moleculeretains almost as many carbon atoms as are present in the initial basicconstituents of the rosin, the number of carbon atoms being reduced onlyby, that number involved in the decarboxylation. Still further, thetypes of constituents of the modified rosin are very few in number,probably not more than two or three, and these constituents arecharacterized by boiling points all lying within a narrow and relativelyhigh temperature range, as can be demonstrated by subsequentdistillation of the modified products. poses, are non-volatile whenexposed to the air.

It is of importance in securing various of the foregoing characteristicsthat the reaction take place without any appreciable concurrentdistillation. In addition, the absence of air and/ or control oftemperature are important in avoiding destructive distillation.

Whatever the exact nature of the chemical colloidal and/or physicalchanges which are brought about, in general the treatment provided inaccordance with the present invention reduces the acid value of themodified product and also softens or liquefies the material. Thesechanges,

factory.

By appropriate selection of modifying agent and treatment conditions,such as temperature, time, vacuum, vetc., I am enabled to controlvarious physical properties of the modified products, and notably theacid value, saponification value and physical consistency. In general,the most valuable modified products have, for instance, a saponiflcationvalue not exceeding about 120.-

Examzs Example 1 The modified products, for practical purployed may besuch that gases evolved from the reaction will serve to effectivelyexclude air, without applying vacuum. Furthermore, certain gases, suchas CO2, or nitrogen can be either bubbled through the reaction mass oremployed as a blanket on the surface of the batch'undergoing treatment;Expedients of this type not onlyserve to exclude the air from thereaction but may also be utilized, for their supplemental effect on thematerial being treated, this subject being more fully considered in mycopending application Serial No. 318,650, filed February 12, 1940 (nowPatent 2,298,270) of which the present application is acontinuation-in-part. It is here 'further noted that certain featuresherein disclosedare also disclosed in my prior U. 5. application SerialNo. 359,425 (now Patent 2,213,- 944); and Serial No. 143,786 (now PatentNo. 2,189,772) l Moreover, as disclosed in the above mentionedapplications, still other variations in process may be employed for anumber of diiferent purposes,

but it is not throught necessary to discuss these fully herein, sincereference may be made to the copending applications for that purpose. Inpassing, however, it is noted that additional treatment agents, of asupplemental character, may also be present during the reaction, amongwhich might be mentioned dissolution promoting agents of the typedisclosed in my issued Patent No. 2,293,038. Various combinations ofmodifying agents may also be used for different purposes, includingcombinations of the modifying agents above disclosed, as well ascombinations of the modifying agents herein disclosed with agents;

disclosed in other of my applications mentioned above as well ashereinafter.

It is further to be noted that in general increasing any one or all ofthe variables: namely, temperature, time of treatment and percentage ofmodifying agent, increases the extent of modification. It will beunderstood that the foregoing is a general rule normally applicablewithin the ranges of operation above indicated, although, as

to at least some variables, there may be limits beyond which the generalrule does not apply.

. For instance, excessive increase in temperature may substantiallyalter the character of the proohbatchofboogramsofwwwocdrosinwas heatedin a one-liter distilling flask for 5 hours at a temperature of 290-295C. and under a pressure of 400 mm. Hz. 80: ass was bubbled through themolten rosin during the 5-hour treatment periodat a rate of 17 grams perhour, 1. e., 3.4% per hour based on the weight of rosin treated.

The acid number of the rosin at the end of the treatment was 131.

Example 2 In this example a batch of 300 grams of ww wood rosin washeated in a one-liter flask imder the same conditions as in Example 1.In this example, however, 80: was bubbled through the batchduring the5-hour treatment period at a rate of 25gramsperhour. Thisisequivalenttoa rate a little above 8% per hour.

The acid value of the final product was 114.5.

Certain variations in procedure may be adopted.

For example, instead of using vacuum during the treatment period, otherprocedure may be adopted with a view to excluding air from the reaction.The form of the reaction vessel cmess. On the other hand, in instanceswhere a soap forming metal is present in the modifying agent, excessiveincrease in percentage of modifyin's asent'may not yield as soft aproduct as a lower percentage of the modifying agent.

In considering the starting material on which the process may beemployed, it is first noted that the process brings about changes bothof a colloidal and also of a chemical nature. It is important, however,to bear in mind that the process essentially involves a' reaction withthe rosin molecule. that is, with the type of molecules of which thebasic constituents'oi natural rosin are composed. Therefore, while rosinitself, such mas gum or wood resins, represents perhaps the mostimportant starting material towhich the process isadaptable, it is notedthat the process -may be employed on rosin which has been pretreated invarious ways, oron mixed or chemical 1y condensed materialsincorporating rosin, since the reaction will take place wherever therosin molecule is present, provided, of course, that the physical orchemical state or environment of the rodnmolecule 3 not such as toprevent the I reaction from taking place.

It may also be mentioned that there are other natural resins, such ascopnls, which act simiii desired, be'subject I larly to rosin bytreatment in accordance with this invention. In fact, the reaction maybe carried out on any of the natural resins containing high molecularresin acids; Therefore, wherever any such other natural resin behavessimilarly to rosin, it is. herein considered as an equivalent.

Copals are iossil gums which have to be iused" before becoming solublein organic solvents and miscible with iatty are used in'the presentprocess. employed in the fused state.

The modified products this invention may,

to other treatment, dependwhich it is intended. Thus,

they should be ing upon the use for ior'example, the modified productsmay be vulcanized with sulphur. The modified resin products securedin-accordance with the foregoing, may be vulcanized as such, or insolutions, such as varnish solutions, (in the latter case with sulphurchloride).

Further, they may be converted into emulsions and used for variouspurposes in that form. In the event sulphur or other sulphur-likevulcanizing a ents are used, vulcanization, for certain purposes, isdesirably carried out at temperatures between about 120 C. and 200 C.For other purposes where vulcanization is to be eirected at lowertemperatures, for instance, at room temperature. sulphur chloride orsimilarly acting vulcanizing agents should be used. In inoil. Whenoopalsstances where the vulcanization is carried out in a varnishsolution, the sulphur chloride treatment is especially practical. v

As is mentioned in my application Serial No. 386,371, flied April 1,1941 (new Patent 2.311.200) the modified rosin roducts maybe subject tostill other supplemental treatments, suchfor instance, as esterincation,as by treating with glycerin or other polrh dric alcohols, such asglycols,

which the treatment temperature is about- 8. A process in accordancewith claim 1 in whicrlgdtge sulphutggimgas is bubbled through the durin!cut 4 dunnr said heatin I

